Abstract

The dynamics of bistability in deformed helix ferroelectricliquid crystal have been investigated by electro-optical method. The threshold value of the voltage required to switch the molecules of deformed helix ferroelectricliquid crystals (DHFLC) material has been studied by applying triangular wave pulse and texture observation under polarizing microscope. Two peaks have been observed in low and high frequency regimes on the application of triangular wave pulse to the sample. It has been proposed that the first peak is due to helix unwinding-winding process and the second is due to molecular reorientation process. The occurrence of double peak has been predicted to have close correlation with the observance of memory effect in DHFLC material, which is critically dependent on frequency and applied voltage, on the application of time delayed square wave pulse to the sample cell. The conditions for dynamic and static memory effects in DHFLC material have also been discussed in detail.

Received 06 October 2007Accepted 02 December 2007Published online 20 February 2008

Acknowledgments:

The authors sincerely thank Dr. Vikram Kumar, director of the National Physical Laboratory, for continuous encouragement and interest in this work. The authors are thankful to Dr. S. S. Bawa for useful discussions. The authors (J.P. and S.K.) are thankful to CSIR, New Delhi for financial assistance.